A liquid crystal panel of an active matrix type liquid crystal display device is composed of two substrates placed in parallel to keep a predetermined space and a liquid crystal filled in the space. One of the two substrates is called an active matrix substrate and the other is called an opposing substrate. In some cases, a 3-color filter of RGB or YMC is provided on the opposing substrate.
As shown in FIG. 9, provided atop of the active matrix substrate are a plurality of gate wires 101 aligned in rows to serve as scanning lines, a plurality of source wires 102 aligned in columns to serve as signal lines, and a plurality of pixels 103 formed in a matrix area of the wires 101 and 102 which intersect at right angles with each other. Also, provided atop of the opposing substrate is a common electrode 104.
Each pixel 103 mainly comprises a pixel electrode 105 and a switching element 106, such as a thin film transistor (TFT). The pixel 103 used herein further comprises an additional capacity 107. Also, a leading terminal 108 and a leading terminal 109 are provided to each gate wire 101 and each source wire 102, respectively.
Recently, there has been an increasing demand for an active matrix substrate with higher definition, and to meet such a demand, a numerical aperture of the pixel 103 has been increasing. One possible method of increasing a numerical aperture is to narrow a space between the pixel electrodes 105 in adjacent pixels 103, but this method poses problems as specified below.
That is, the shorting of the pixel electrodes 105 in two adjacent pixels 103 occurs if the patterning during the fabrication sequence of the active matrix substrate is defective and the pixel electrodes 105 are not separated completely. Or even when the pixel electrodes 105 in two adjacent pixels 103 are separated completely, the shorting occurs if scraps of electrode conductive films of the switching element 106 fall in the space between the pixel electrodes 105 during the pattering step.
When this kind of shorting occurs in a longitudinal direction of the gate wire 101, two kinds of source signals written into the pixel electrodes at the timing of the same gate signal are mixed, and a potential of each shorted pixel 103 is brought to an intermediate potential, whereby a display defect occurs. The display defect becomes noticeable when the liquid crystal panel is driven by providing a display signal having alternating polarities to a plurality of source wires 102, because two source signals having different polarities are impressed on the adjacent pixel electrodes, respectively. On the other hand, when the shorting occurs in a longitudinal direction of the source wire 102, two shorted pixels 103 are driven by the writing action of the switching element 106 in either pixel 103 whichever has the later gate signal input timing. Thus, a source signal written by the switching element 106 in the other pixel 103 having the earlier gate signal input timing must be cancelled. However, this makes the writing action by the switching element 106 in the pixel 103 having the later input timing difficult, which results in a display defect.
Incidentally, the fabricated active matrix substrate is subject to inspection, and if any shorting is discovered, a laser beam is irradiated to the shorting spot to remove a material causing the shorting. However, since such a short-causing material is in an extremely narrow space between the pixel electrodes 105, it is tedious and inefficient to set an irradiation point and only a quite low success rate is achieved. Moreover, the fragments of the removed material may fall in the space between the pixel electrodes 105 again and cause the shorting at a different spot. Therefore, the above conventional method needs improvement.